Light weight construction steel



Patented Aug. 29, 1939 P TsNT OFF-ICE v 2,111,375 LIGHT WEIGHT CONSTRUCTION s'rEsL Byramji D. saklatwallafittsburgli, Pa.

No Drawing.

Claims.

This invention relates to alloy steels of high physical properties but containing comparatively low percentages of alloying elements. For the hightensile properties of these steels carbon is not the element mainly relied upon but such properties are achieved by the proper combination of the alloying elements, the individual elements making such a combination being present in comparatively small amounts. therefore, of these steels can be comparatively very low so that by the term steels I include faerrous alloys with as low a carbon content as The present application is a continuationrin- 5 part of my application Serial No. 61,060, filed January 27,1936. a

It is desirable to obtain steels which have physical properties and resistance to corrosion superiorto ordinary carbon steels at a cost only a trifle 20 higher than-plain carbon steels of equal carbon content. It is possible by the proper selection of the alloying elements to produce alloy steels costing only slightly more than carbon steel of equal carbon content weight for weight. However, :5 when the cost of a completed structure or a unit built of such alloy is considered, such structure or unit may prove cheaper even in spite of the higher steel price owing to the possibility of using lighter sections, due to higher strength and greater corro- 3L) sion resistance and thus curtailing the total weight of the finished unit. This advantage becomes particularly marked in the case of transportation .units, 'such' as railroad cars, trucks,

buses, and the like, where the; hauling of dead, weight is a detrimental factor, so that any cur-.

tailment in weight permissible-by the higher physical properties of the steel in the construction of such units reflects not only in the initial low cost of the unit but what is -even more important 0 in the 'cost of operation of such unit.

For the production of higher tensile steels, various alloying elements have been utilized but most oi these elements or their combinations in use atpresent have certain disadvantages. For in- 45 stance, in the case of manganese steel containing about 1% to 1.5% 01 manganese, higher tensile strength and yieldpoint are obtained but such manganese content has an embrittling effect on the steel which limits its applicability for struc- 5o tural purposes. Similarly, steelsof high silicon content of approximately 1% have higher physical properties but such steels are not ,satisiac-' tory in bending, forming and such like operations where a satisfactory deflection is demanded from 55 the steel. .Copper has been utilized for impart- The carbon content,-

are free from inclusionsrsea ms, surface defects,

. found that it is necessary to use these elements Application December 10, 1937, Serial No. 179,102

ing tensile properties but in order to obtain suflicien't advantage a fairly high percentage of copper .air hardening qualities which are undesirable,

especially if such steels are to be constructed into units by welding. Phosphorus has been lately recommended as an alloying element in steel and it ,imparts certain desirable physical properties-but 'by itself it has the objectionable property of cold-shortness and also of non-uniformity or segregation in the cast or wrought body of steel containing it; Other elements, such as cobalt, tungsten, vanadium and the like, are used in high tensile steels but their excessive cost is a marked disadvantage so that such steelscannot be gen.- erally utilizedfor structural purposes in competition with carbon' steels.

By the composition of my invention, I have obviated these deficiencies and produced an alloy steelfiwith comparatively low percentages of alloying elements and consequently at a cheap cost, by the ordinary steel making processes. In the selection of the alloying elements, I have utilized cheap alloys and those which give a good recovery in re-melting from scrap. Further, the ele-.- ments used do not produce difliculties in the rolling and fabricating operations of the steels which and the like, and therefore fabricable with equal ease .as carbon steels. The combination ofalloying elements I use for my composition consists of silicon, copper nick el and phosphorus. I have 40 in certain definite proportions, in balance against each other, in order not only to offset the deleterious properties of the individual elements but also to obtain a novel combination of salutary properties not anticipatable from the individual effects of ,the'eleme nts.

It is well known that silicon, when added to carbon steel, raises the tensile strength, but very deleteriously-a'ffects ductility and impact properties; This is due to the fact that silicon dissolves in the ferrite and brings about a hardening and consequent brittleness of the ferrite. I have .found, however, that, when thesilicon is combined withv nickel and copper forming silicides' of alone does without the deleterious brittleness.

I have discovered thatadvantage can be taken 01? the higher physical properties imparted to steel by silicon, thus taking advantage of the cheap price of silicon as an alloying element. Such advantage is obtained by the addition of the proper combination of copper, nickel and phosphorus to the steel containing silicon. The coarseness of structure, brittleness, lack of deflection and other adverse properties due to the silicon are entirely suppressed and ductility is imparted by the copper, nickel and phosphorus. Also,,by this combination desirable impact values are obtained. The deleterious properties of phosphorus are offset by the proper balanced combination of silicon, copper and nickel. Further, steels of this composition are easily weldable by the commercial processes of welding in spite of the high silicon content. I have, however, found that these elements have to be within certain narrow ranges in relation to the silicon'content and also in relation to each other to bring about these desired properties in the final steel.- I have found that I obtain steels with good welding properties and of considerably higher tensile strength, yield point, elongation and reduction of area than ordinary carbon steels of equal carbon content, provided the elements of my steel are within the following general limits:

Percent Carbon 01 to .25 Silicon 60 to 1. 5 Copper .25 to .60 Nickel to 1. 25 Phosphorus 10 to .25

I have iound that the other elements usually occurring in steel should be as low as possible,

- although they do not appreciably alter the physical properties of my steel when present in the amount generally found in ordinary plain carbon steels. The physical properties of my steel are derived from the balanced combination of the .obtain the. physical properties. essential tohave these ele ents in as low aperelements silicon, nickel, copper and phosphorus.

Therefore, the usual strength imparting elements found in ordinary steel such as manganese, chromium and molybdenum are not utilized to centage as possible. It is, owever, well recognized that by the present-dayordinary'processes offsteel making it is not possible to exclude the presence of slight percentages of most of the alloying elemen 'in all finished steel, even in ordinarycarbon s 1. Such residual percentages, for instance of manganese up to 160%, of chromium up to 25%, and molybdenum up to about .10% canbe present in my steel without exerting I any deleterious effect. I' prefer to have the man- 'my steels, in quantitiesgenerally used for this purpose, donot appreciably alter their properties I and can be present.

I have found the most usefiil steels from thestandpoint of good physical properties combined In fact, kit: is

T these elements, and such sllicides are dissolved with an extremely reasonable commercial cost of production to lie within the following limits:

to the extent of small fractions of a per cent.

For ordinary structural purposes, such as for the construction of machinery parts, hoppers, chutes, tanks, car bodies, passenger coach bodies, and for the construction of other units generally made out of common steel, I have found that the Percent Carbon 04 to 18 Silicon 65 to 1 Copper 25 to 50 Nickel; 50 to 1. 00

Phosphorus 10 to .18

Manganese to Sulphur 1 02 to 05 following composition of my steel is extremely cost - Percent Carbon .08 to .12 Silicon .75 to .90 Copper .30 to .45 Nickel 65 to 85 Phosphorus 12 to 15 Manganese under .35 Sulphur under .05

It is well known that strength imparting elementssuch as carbon and silicon when added to steel increase the tensile strength and at the same time increase the yield point to a. certain extent. The tensile strength, however, with increasing amounts of carbon or silicon increases at a much faster rate than does the yield point. For certain engine'eringfdesigns, it is essential to have a high yield point with a correspondingly lower tensile strength than would be present if the yield point were obtained, for instance, by carbon. I have obtained such comparatively high yield point by the simultaneous addition of nickel and copper in the presence of the high silicon content. In my steel, the yield point is at least about 70%, and in certain cases up to and over 85% of the tensile strength. My steel is characterized by a tensile strength 'inthe as-rolled' condition' of about 65,000 to 80,000 poundsper square inch,

and further characterized by a ductility anddeformability at least equal to that of a carbon steel of corresponding strength, together with good capability of being welded by the ordinary commercial processes of welding.

The steels f my invention can be manufactured by the 'ordin ry steel making'processes in combustion heated furnaces, such as the open hearth or Bessemer. They can also be made in the electric furnace either of the are or induction type.

The steels can be cast into ingots and then rolled into requiredshapes and forms for the manu-' 'facture of products ordinarily produced by steel mills. The steels can also be cast in molds for the production of castings, following the usual steel foundry practice.

The alloying elements of my'steel, namely; sili- I con, copper,'nickel, phosphorus, can be introduced into the steel according to usual alloying practice. After the melting down of the*steel, the bath can be ,deoxidized with silicon in the form of ferro silicon of 15% or grade and the high silicon conterrt pfthe finished steel .canbe preferably ,sulpliur, the balance being substantially all iron,

.incorporated and controlled by addition of silican in the form of or ferro silicon in the ladle. The copper and nickel being nonoxidizable elements are preferably added in the early stages of the melting of the steel. These elements being ,non-o xidizable it is easy to control their predetermined contents in the finished steel. The phosphorus can be added in the form of ferro phosphorus of the usual commercial percentages in the furnace after deoxidation with silicon and just before tapping the steel. However, in order to minimize waste due to oxidation of the phosphorus, it is preferable to add all or at least the main bulk of the ferro phosphorus in the ladle during the tapping of the steel. The phosphorus content is thus obtained with greater exactitude and of predetermined magnitude in the finished steel. If aluminum is used in the manufacture of my alloy steel, it can be added in the ladle or in the moulds according to the usual steel ingot casting practice.

Alloy steels of my invention can be subjected to any of the heat-treating operations as carricd out for ordinary carbon steels. For instance, in the case of sheets and plates for certain purposes, their characteristics can be altered by annealing, normalizing, etc., just as in the case of these products made from ordinary carbon steel. Similarly, the steels, especially those with carbon content on the high side of the range given above, can be hardenedby heating to above their critical ranges and then cooling in air, oil, or water as desired.

The present invention is not limited to the proportions set forth in the illustrative embodiments but may be otherwise embodied withimthe scope of the following claims.

I claim:

1. A low carbon alloy steel of high physical properties containing about, .01 to 25% carbon, about .60 to 1.50% silicon, about .25 to .60% copper, about .50 to 1.25% nickel, about .10 to 25% phosphorus, under .60% manganese, under .10% sulphur. the balance being substantially all iron,

the alloy steel being free from chromium in amount to exert a noticeable effect on its properties and being always less than 25%, and characterized by a tensile strength in the as-rolled condition of about 65,000 to 80,000-pounds per square inch, the yield point being over about 70% of the tensile strength, and further characterized by a ductility and deformability at least equal to that of carbon steel of corresponding strength, together with good capability of being welded by the ordinary commercial processes of welding.

2. A low carbon ailoy'steel-of high physical properties containing about .04 to 18% carbon,

the 'alloy steel being free from chromium in amountto exert a noticeable eflect on its properties and beirig always less than 25%, and characterized by a tensile strength in the as-rolled condition of about 65,000 to 80,000' pounds per square inch, the yield point being over about 70% of the tensile strength, and furthencharacterized by a ductility and deformability at least equal to that of carbon steel of corresponding strength, together with good capability of being welded by the ordinary commercial processes of welding. I

3. A low carbon alloy steel of high physical properties containing about .08 to .12% carbon,

, about .75 to .90% silicon, about .30 to .45% copper, about .65 to 1.25% nickel, about .12 to .15% phosphorus, not over 35% manganese, under- .10% sulphur, the balance substantially all iron, the alloy steel being free from chromium in amount to exert a noticeable effect on its properties and being always less than 25%, and characterized by a tensile strength in the as-rolled condition of about 65,000 to 80,000 pounds per square inch, the yield point being over about 70% of the tensile-strength, and further characterized by a ductility and deformability at least equal to that of carbon steel 01' corresponding strength, together with good capability of being welded by the ordinary commercial processes of welding.

. 4. A low carbon alloy steel .of' high physical properties containing about .01,to 25% carbon, about .60 to 1.50% silicon, about .25 to .60% copper, about .50 to 1.25% nickel, about .10 to 25% phosphorus, .under .60%manganese, under .10%

sulphur, the total of the nickel and copper being about 65,000 to 80,000 pounds per square inch,

the yield point being over about 70% of the tensilestrength, and further characterized by a ductility and deformability at least equal to that of carbon steel of corresponding strength, together with good capability of being welded by the ordinary commercial processes of welding.

5. A low'carbon alloy steel of high physical properties containing about .01 to 25% carbon, about .60 to 1.50% silicon, about .25 to .60% copper, about .50 to 1.25% nickel, about .10 to 25% phosphorus, under .60% manganese, under sulphur, the balance being substantially. all iron, the alloy steel being free from chromium in amount to exert a noticeable effect on its properties and being always less than 25%.

BYRAMJI D.- SAKLA'I'WALLA.

Patent No 2,171,575.

CERTIFICATE OF CORRECTION. v

- 2 August 29, 19590 BYRAMJI DqsAmTwALm} It is hereby certified that error appears tn the printed-epeetficatlon of the above numbered patent requiring correction as follows: Page 3, sec- 0nd column, "11m; 18, claim 3, for "55%" remi -55%; and that the eaid'1nt t'era Patent ahouldbe read with this o'orrection thereiri that the eame may conform to the record of the case in the Patent Office} Signed. and. sealed this 3rd day of October, A. D. 1939.

Henry Van Aredalle, Acting Coinmiefiioner of Patents. 

